Display manager

A display manager, or login manager, is typically a graphical user interface that is displayed at the end of the boot process in place of the default shell. There are various implementations of display managers, just as there are various types of window managers and desktop environments. There is usually a certain amount of customization and themeability available with each one.

Run ~/.xinitrc as a session

Installing xinit-xsessionAUR will provide an option to run your xinitrc as a session. Simply set xinitrc as the session in your display manager's settings and make sure that the ~/.xinitrc file is executable.

Starting applications without a window manager

You can also launch an application without any decoration, desktop, or window management. For example to launch google-chromeAUR create a web-browser.desktop file in /usr/share/xsessions/ like this:

In this case, once you login, the application set with Exec will be launched immediately. When you close the application, you will be taken back to the login manager (same as logging out of a normal DE/WM).

It is important to remember that most graphical applications are not intended to be launched this way and you might have manual tweaking to do or limitations to live with (there is no window manager, so do not expect to be able to move or resize any windows, including dialogs; nonetheless, you might be able to set the window geometry in the application's configuration files).